宏观经济学.ppt

ECONOMICS:Principles and Applications 3eHALL&LIEBERMAN 2005 Thomson Business and Professional PublishingSlides by:John&Pamela HallThe Classical Long-Run Model1The Classical Long-Run ModelEconomists sometimes disagree with each otherActually much more agreement exists among economists than there appears to beOnce distinction between long-run and short-run becomes clearMany apparent disagreements among macroeconomists dissolveIf no time horizon is specified,however,an economist is likely to focus on horizon he or she feels is most importantSomething about which economists sometimes do disagree2The Classical Long-Run ModelIdeally,we would like our economy to do well in both long-run and short-runUnfortunately,there is often a trade-off between these two goalsDoing better in short-run can require some sacrifice of long-run goals,and vice versaPolices that can help us smooth out economic fluctuations may prove harmful to growth in the long-runWhile policies that promise a high rate of growth might require us to put up with more severe fluctuations in short-run3Macroeconomic Models:Classical Verses KeynesianClassical model,developed by economists in 19th and early 20th centuries,was an attempt to explain a key observation about economyOver periods of several years or longer,economy performs rather wellIf we think in terms of decades rather than years or quarters,business cycle fades in significance In the classical view,this behavior is no accidentPowerful forces are at work that drive economy towards full employmentAn important group of macroeconomists continues to believe that classical model is useful even in shorter runIn 1936,in midst of Great Depression,British economist John Maynard Keynes offered an explanation for economys poor performanceArgued that,while classical model might explain economys operation in long-run,long-run could be a very long time in arriving4Macroeconomic Models:Classical Verses KeynesianKeynesian ideas became increasingly popular in universities and government agencies during 1940s and 1950sBy mid-1960s,entire profession had been won overMacroeconomics was Keynesian economicsClassical model was removed from virtually all introductory economics textbooksClassical model is still importantIn recent decades there has been an active counterrevolution against Keyness approach to understanding the macroeconomyUseful in understanding economy over long-runWhile Keyness ideas and their further development help us understand economic fluctuationsmovements in output around its long-run trendClassical model has proven more useful in explaining the long-run trend itself5Assumptions of the Classical ModelAll models begin with assumptions about the worldClassical model is no exceptionMany of its assumptions are simplifyingMake model more manageable,enabling us to see the broad outlines of economic behavior without getting lost in detailsOne assumption in classical view that goes beyond mere simplificationMarkets clearPrice in every market will adjust until quantity supplied and quantity demanded are equal6Assumptions of the Classical ModelMarket-clearing assumption provides hint about why classical model does a better job over longer time periods(several years or more)than shorter onesWell use classical model to answer a variety of important questions about economy in long-run,such asHow is total employment determined?How much output will we produce?What role does total spending play in the economy?What happens when things change?7How Much Output Will We Produce?How can we disentangle web of economic interactions we see around us?Decide which market or markets best suit the problem being analyzed,and Identify buyers and sellersIdentify type of environment in which they tradeBut which market should we start with?Logical start is market for resourcesLabor,land and natural resources,capital and entrepreneurshipWell concentrate our attention on laborOur question isHow many workers will be employed in the economy?8Figure 1:The Labor Market9The Labor MarketLabor supply curve slopes upward Becauseas wage rate increasesmore and more individuals are better off working than not workingThus,a rise in wage rate increases number of people who want to workto supply their laborAs wage rate increases each firm will find thatto maximize profitit should employ fewer workers than beforeWhen all firms behave this way together a rise in wage rate will decrease quantity of labor demanded This is why economys labor demand curve slopes downwardIn classical view,economy achieves full employment on its own10Determining the Economys OutputMost effective way to master a macroeconomic model is“divide and conquer”Start with part of model,understand it well,and then add in other partsAccordingly,our classical analysis of economy is divided into two separate questionsWhat would be the long-run equilibrium of the economy if there were a constant state of technology And if quantities of all resources besides labor were fixed?What happens to this long-run equilibrium when technology and quantities of other resources change?11The Production FunctionRelationship between total employment and total production in the economyGiven by economys aggregate production functionShows total output economy can produce with different quantities of laborGiven constant amounts of other resources and current state of technologyIn classical,long-run view economy reaches its potential output automaticallyAn important conclusion of classical model and an important characteristic of the economy in long-runOutput tends toward its potential,full-employment level on its own,with no need for government to steer the economy toward it12Figure 2:Output Determination in the Classical Model13The Role of SpendingWhat if business firms are unable to sell all output produced by a fully employed labor force?Economy would not be able to sustain full employment for very longIf we are asserting that potential output is an equilibrium for the economyHad better be sure that total spending on output is equal to total production during the yearBut can we be sure of this?In classical view answer is yes14Total Spending in a Very Simple EconomyImagine a world with just two types of economic unitsHouseholds and business firmsCircular FlowA diagram that shows how goods,resources,and dollar payments flow between households and firmsIn a simple economy with just households and firms in which households spend all of their incomeTotal spending must be equal to total outputKnown as Says Law15Figure 3:The Circular Flow16Total Spending in a Very Simple EconomySays Law named after classical economist Jean Baptiste Say(1767-1832),who popularized the ideaIn Says own words“A product is no sooner created than it,from that instant,affords a market for other products to the full extent of its own valueThus,the mere circumstance of the creation of one product immediately opens a vent for other products”Says law states that by producing goods and servicesFirms create a total demand for goods and services equal to what they have produced orSupply creates its own demand17Total Spending in a More Realistic EconomyDoes Says law also apply in a more realistic economy?In the real worldHouseholds dont spend all their incomeRather,some of their income is saved or goes to pay taxesHouseholds are not the only spenders in the economyBusinesses and government buy some of the final goods and services we produceIn addition to markets for goods and resources,there is also a loanable funds market Where household saving is made available to borrowers in business or government sectors18Some New Macroeconomic VariablesPlanned investment spending(IP)over a period of time is total investment spending(I)minus change in inventories over the periodIP=I inventoriesNet taxes(T)are total government tax revenue minus government transfer paymentsT=total tax revenue transfersHousehold saving(S)Its often useful to arrive at household saving in two stepsDetermine how much income household sector has left after payment of net taxesHousehold sectors disposable incomeDisposable Income=Total Income Net TaxesPart that is not spent is defined as saving(S)S=Disposable Income CTotal Spending in ClassicaIn Classica,total spending is sum of purchases made by household sector(C),business sector(IP),and government sector(G)Total spending=C+IP+G19Some New Macroeconomic VariablesSaving and net taxes are called leakages out of spendingAmount of income that households receive,but do not spendThere are also injectionsspending from sources other than householdsA governments purchases of goods and servicesPlanned investment spending(IP)Total spending will equal total output if and only if total leakages in the economy are equal to total injectionsOnly if sum of saving and net taxes is equal to sum of planned investment spending and government purchases20Figure 4:Leakages and Injections21The Loanable Funds MarketWhere households make their saving available to those who need additional fundsTotal supply of loanable funds is equal to household savingFunds supplied are loaned out,and households receive interest payments on these fundsBusinesses demand for loanable funds is equal to their planned investment spendingFunds obtained are borrowed,and firms pay interest on their loansBudget deficitExcess of government purchases over net taxesBudget of surplusExcess of net taxes over government purchasesWhen government purchases of goods and services(G)are greater than net taxes(T)Government runs a budget deficit equal to G TWhen government purchases of goods and services(G)are less than net taxes(T)Government runs a budget surplus equal to T-G22The Supply of Funds CurveSince interest is reward for saving and supplying funds to financial marketRise in interest rate increases quantity of funds supplied(household saving),while a drop in interest rate decreases itSupply of funds curveIndicates level of household saving at various interest ratesQuantity of funds supplied to the financial market depends positively on interest rateThis is why the saving,or supply of funds,curve slopes upwardOther things can affect savings besides the interest rate,includingTax ratesExpectations about the futureGeneral willingness of households to postpone consumption23Figure 5:Supply of Household Loanable Funds24The Demand for Funds CurveWhen interest rate falls investment spending and the business borrowing needed to finance it riseBusiness demand for funds curve slopes downwardWhat about governments demand for funds?Will it,too,be influenced by the interest rate?Probably not very muchGovernment seems to be cushioned from cost-benefit considerations that haunt business decisionsAny company president who ignored interest rates in deciding how much to borrow would be quickly out of a jobU.S.presidents and legislators have often done so with little political costGovernment sectors deficit and its demand for funds are independent of interest rateAs interest rate decreases quantity of funds demanded by business firms increasesWhile quantity demanded by government remains unchangedTherefore,total quantity of funds demanded rises25Figure 6:Business Demand for Loanable Funds26Figure 7:The Demand for Funds27Equilibrium in the Loanable Funds MarketIn classical view loanable funds market is assumed to clearInterest rate will rise or fall until quantities of funds supplied and demanded are equalCan we be sure that all output produced at full employment will be purchased?28Figure 8:Loanable Funds Market Equilibrium29The Loanable Funds Market and Says LawAs long as loanable funds market clears,Says law holdsTotal spending equals total outputThis is true even in a more realistic economy with saving,taxes,investment and government deficitHeres another way to see the same result,in terms of a simple equationLoanable funds market clears S=IP+(G T)Rearranging this equation by moving T to left sideLoanable funds market clears S+T=IP+GSays law shows that total value of spending in economy will equal total value of outputRules out a general overproduction or underproduction of goods in the economyIt does not promise us that each firm will be able to sell all of the particular good it produces30Figure 9:An Expanded Circular Flow31The Classical Model:A SummaryBegan with a critical assumptionAll markets clearIn classical model,government neednt worry about employmentEconomy will achieve full employment on its ownIn classical model,government neednt worry about total spendingEconomy will generate just enough spending on its own to buy output that a fully employed labor force produces32Using the Theory:Fiscal Policy in the Classical ModelCould government increase economys total employment and total output by raising total spending?Two ideas for increasing spending come to mindGovernment could simply purchase more output itselfMore goods,like tanks and police cars,or more services,like those provided by high school teachers and judgesGovernment could cut net taxes,letting households keep more of their incomeSo they would spend more on food,clothing,furniture,new cars,and so onFiscal policy is a change in government purchases or in net taxes Designed to change total spending in the economy and thereby influence levels of employment and outputIdea behind fiscal policy sounds sensible enoughBut does it work?Not if economy behaves according to classical model33Using the Theory:Fiscal Policy With A Budget DeficitWhat would happen if the government of Classicawhich is running a deficitattempted to increase employment and output by increasing government purchasesCrowding out is a decline in one sectors spending caused by an increase in some other sectors spendingIn classical model a rise in government purchases completely crowds out private sector spending so total spending remains unchangedIn classical model,an increase in government purchases has no impact on total spending and no impact on total output or total employmentOpposite sequence of events would happen if government purchases decreasedTotal spending and total output would remain unchanged34Figure 10:Crowding Out With An Initial Budget Deficit35Fiscal Policy With A Budget SurplusTotal spending remains unchanged,and fiscal policy is completely ineffectiveSame conclusion we reached about fiscal policy with a government budget deficitOur exploration of fiscal policy shows us that,in long-runGovernment efforts to change total output by changing government spending or taxes are unnecessary and ineffective36Figure 11:Crowding Out With An Initial Budget Surplus37此课件下载可自行编辑修改，供参考！感谢您的支持，我们努力做得更好！